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The Paleozoic Portal

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Introduction

The Paleozoic (or Palaeozoic) Era (/ˌpæl.i.əˈzoʊ.ɪk, -i.oʊ-, ˌpeɪ.li.ə-, -li.oʊ-/ pal-ee-ə-ZOH-ik, -⁠ee-oh-, pay-lee-, -⁠lee-oh-; from the Greek palaiós (παλαιός), "old" and zōḗ (ζωή), "life", meaning "ancient life") is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 538.8 to 251.902 million years ago, and is subdivided into six geologic periods (from oldest to youngest): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.

The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, synapsids and diapsids all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, large, sophisticated synapsids and diapsids were dominant and the first modern plants (conifers) appeared.

The Paleozoic Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover. Recovery of life in the sea may have been much faster. (Full article...)

Selected article on the Paleozoic world and its legacies

A modern mesothelan spider.
Spiders (order Araneae) are air-breathing arthropods that have eight legs and chelicerae with fangs that inject venom. They are the largest order of arachnids. Spiders are found nearly worldwide in nearly every habitat with the exception of air and sea. Anatomically, spiders differ from other arthropods in that the usual body segments are fused into two tagmata, the cephalothorax and abdomen, and joined by a small, cylindrical pedicel. Spiders generally have very centralized nervous systems for arthropods. Their abdomens bear appendages that have been modified into spinnerets that extrude silk from up to six types of silk glands within their abdomen. Spider webs vary widely in size, shape and the amount of sticky thread used. Spiders' guts are too narrow to take solids, and they liquidize their food by flooding it with digestive enzymes and grinding it with the bases of their pedipalps.

Spider-like arachnids with silk-producing spigots appeared in the Devonian period about 386 million years ago, but these animals apparently lacked spinnerets. True spiders have been found in Carboniferous rocks from 318 to 299 million years ago, and are very similar to the most primitive surviving order, the Mesothelae. The main groups of modern spiders, Mygalomorphae and Araneomorphae, first appeared in the Triassic period, before 200 million years ago. (see more...)

Selected article on the Paleozoic in human science, culture and economics

The title page of the 1859 edition of On the Origin of Species.
On the Origin of Species, published in 1859, is a work of scientific literature by Charles Darwin which is considered to be the foundation of evolutionary biology. Darwin's book introduced the scientific theory that populations evolve over the course of generations through a process of natural selection. It presented a body of evidence that the diversity of life arose by common descent through a branching pattern of evolution. Darwin included evidence that he had gathered on the Beagle expedition in the 1830s and his subsequent research findings. Ideas about the transmutation of species were controversial as they conflicted with beliefs that species were unchanging parts of a designed hierarchy and that humans were unique and unlike animals.

The book was written for non-specialist readers and attracted widespread interest upon its publication. As Darwin was an eminent scientist, his findings were taken seriously and the evidence he presented generated scientific, philosophical, and religious discussion. Within two decades there was widespread scientific agreement that evolution, with a branching pattern of common descent, had occurred, but scientists were slow to give natural selection the significance that Darwin thought appropriate. During the "eclipse of Darwinism" from the 1880s to the 1930s, various other mechanisms of evolution were given more credit. With the development of the modern synthesis in the 1930s and 1940s, Darwin's concept of evolutionary adaptation through natural selection became central to modern evolutionary theory, and it has now become the unifying concept of the life sciences. (see more...)

Selected image

Holotype of Furca mauritanica. Early Ordovician (Upper Fezouata Formation).

Holotype of Furca mauritanica. Early Ordovician (Upper Fezouata Formation).
Photo credit: Didier Descouens

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Methanosarcina barkeri fusaro.

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Topics

Geochronology - Cambrian (Early - Middle - Late) - Ordovician (Early - Middle - Late) - Silurian (Early - Wenlock - Ludlow - Late) - Devonian (Early - Middle - Late) - Carboniferous (Mississippian - Pennsylvanian)- Permian (Early - Middle - Late)

Paleozoic landmasses - Pannotia - Baltica - Laurentia - Siberia - Avalonia -Gondwanaland - Laurentia - Euramerica - Gondwana - South China- Pangaea

Major Paleozoic events - Cambrian Explosion - Cambrian substrate revolution - End-Botomian mass extinction - Cambrian–Ordovician extinction event

Cambrian biota appearances - Brachiopods - Burgess shale fauna - Cephalopods - Chitons - Crustaceans - Echinoderms - Foraminiferans - Graptolites - Radiolarians -Trilobites - Vertebrates

Ordovician biota appearances - Conodonts - Echinoids

Silurian biota appearances - Fungi - Galeaspids - Heterostracans - Land plants - Pituriaspids -Ray-finned fishes - Scorpions - Trigonotarbids

Devonian biota appearances - Crabs - Ferns - Harvestmen - Lichens - Lycophytes - Mites -Springtails - Stoneworts - Trimerophytes

Carboniferous biota appearances - Amphibians - Hagfishes - Insects - Ratfishes - Reptiles -Synapsids

Permian biota appearances - Beetles - Pelycosaurs - Temnospondyls - Therapsids

Fossil sites - Bear Gulch Limestone - Beecher's Trilobite Bed - Gilboa Forest - Grenfell fossil site - Hamilton Quarry - Mazon Creek fossil beds - Mississippi Petrified Forest - Walcott Quarry - Walcott–Rust quarry - Yea Flora Fossil Site

Stratigraphic units - Burgess Shale - Chazy Formation - Columbus Limestone - Fezouata formation - Francis Creek Shale - Gogo Formation - Holston Formation - Hunsrück Slate - Jeffersonville Limestone - Karoo Supergroup - Keyser Formation - Kope Formation - Llewellyn Formation - Mahantango Formation - Maotianshan Shales - Marcellus Formation - Millstone Grit - New Albany Shale - Old Port Formation - Old Red Sandstone - Potsdam Sandstone - Red Beds of Texas and Oklahoma - Rhynie chert - Shawangunk Formation - St. Peter Sandstone - Tuscarora Formation

History - History of paleontology - Timeline of paleontology - The Great Devonian Controversy

Researchers - Charles Emerson Beecher - Ermine Cowles Case - Edward Drinker Cope - Henry De la Beche - Stephen Jay Gould - Increase A. Lapham - Charles Lapworth - Simon Conway Morris - Roderick Murchison - Alfred Sherwood Romer - Neil Shubin - Charles Doolittle Walcott

Culture - Animal Armageddon - The Day The Earth Nearly Died - List of creatures in the Walking with... series - Lost Worlds, Vanished Lives - Miracle Planet - Prehistoric Park - Sea Monsters - Treatise on Invertebrate Paleontology - Vertebrate Paleontology - Walking with Monsters - Wonderful Life

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This page was last updated at 2022-08-09 23:36 UTC. Update now. View original page.

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